Electronic keying device



8, 1950 H. BEECHER 2,517,538

ELECTRONIC KEYING DEVICE Filed May 3, 1946 4 Sheets-Sheet 1 FIG. 2

1 .HARRY BE ECHER 1950 H. BEECHER 2,517,538

ELECTRONIC KEYING DEVICE Filed May 3, 1946 4 Sheets-Sheet 5 gwuawvfom HARRY BEECHER g- 1950 H. BEECHER 2,517,538

ELECTRONIC KEYING DEVICE Filed May 3, 1946 4fSheets-Sheet 4 FIG. 7

.8 grvum'vtom HARRY BEEGHER Patented Aug. 8, 1956 UNITED STATES PATENT OFFICE (Granted under theact of March 3, 1883, as amended April 30, 1928; 3:70 1.0. G. "757) 14 Claims.

Myinvention relates to keying systems and particularly to systems for automatically forming a dot, a dash or -a succession of dots and dashes properlyspaced in response to manipulation of a manually-operated key or equivalent.

In accordance with my invention, the mark and space impulses utilized in keying are produced by a multivibrator which is triggered by an oscillation generator, preferably a relaxation oscillator, controlled by a manually-operated, or other type, key. More particularly inaccordance with my invention, the time-constants of the multi-vibrator.areselected to produce dots or 'daslies concurrently with movement of the key which initiates operation of .the oscillator.

Further in accordance with my invention, the keying impulses are applied to a relay which is isolated from the multi-vibrator by an electronic tube or tubes directly coupled to the multi-vibrator: in some modifications particularly suited for high-speed keying, the relay is of polarized type having windings in the anode circuits of tubes respectively concurrently receiving both positive and negative pulses from the multivibrator.

Further in accordance with some forms of my invention, to ensure proper length of the mark impulses, there are provided electronic hold in circuits whose operation is initiated by operation of the key and which are effective, despite subsequent change in position of the key, until the multi-vibratorhas.completed a mark impulse of predetermined duration.

My invention .further resides in features of combination and arrangement hereinafter described and claimed.

For an understanding. of my invention andior illustration of various embodiments thereof, reference is made to the accompanying drawing. in which:

Assuming the movable contact of key" K has been in neutral position for appreciable time, the following conditions obtain; the anodecurrentof tube VI, as determined by its grid bias derived from resistor RI, sufficiently energizes relay Ry to hold its keying contacts open; tube V2 is also conductive since atthis time no current is flowing through resistors R2, BIZ and Rid in-circuit between the control grid and cathode of that tube: tube V3 isnot conductive becauseits negative grid-biasing potential, derived from resistor R5 of'the voltage-divider network R5, R5, is sufiicient to overcome thepositive potential applied to thegrid through resistor R4: and theconclenser C5 is chargedto'a potential suitably above the ionizationpotential of the discharge tube V4 at this time inan open-circuit.

"When the movable contact-of key K is moved from neutral-position to engage contact '2 or 3, the condenser 'C5 discharges practically instantaneously through tube V4 and resistance RH] which is includedin the circuit to limit the peak dischargecurrent to magnitude which does not damagetubevfl. This-sudden discharge of condenserJCE produces a-brief pulse applied through condenser C l to grids of tubes Vi and V2. The pulse is of negative polarity and therefore cuts off flow of anode current in tubes VI and V2. Moreover 'tube V2 amplifies and inverts the pulse applying it asiailarger positive pulse to the control grid of tube V3 which in turn reinverts the pulse and applies, it through condenser03 as a Fig. 1 is a circuit diagram of the basic system.

highly amplified negative pulse to the grids of tubes VI and V2. In consequence of this regenerativeiactiomthe relay current is abruptly terminated or abruptly reduced well below contactholding magnitude and the keyingcontacts of relay Ry therefore sharply move ,to closedcircuit position to start a mark period. By virtue of the highly positive bias now applied to its grid, the tube V3 passes maximum plate current.

The negative charge appliedtothe grids of tubes VI and V2 leaks off through a path including resistors R2, R|3 and RIZ ,if the key is in dash position or through a path including resistors R2, RIB if the key is in dot position. In the latter position, the resistonRlE is shunted out of the leakage path through, a circuit including contact I otthekey.

The mark period, or period of closure of the relay contacts, continues until the negative charge of condenser C3 falls below cut-ofi at whichtime'tube V2 starts to conduct current causing the grid of tube V3 to become less positive. irThe .lesulting lamplified positive pulse is applied to thegrids of tubesvl and V2, and in 3 effect the remaining negative charge is practically instantaneously nullified with result the relay current is abruptly increased and the relay contacts sharply and cleanly separate to start a space.

The tubes VI and V2 are now conducting and tube V3 is cut off and the condenser C5 recharges through the resistors Rl, R8 and R9.

If the ke is held closed, the tube V i fires when the condenser voltage rises to the ionization potential of the gas and another mark starts, the above sequence repeating so long as the key is held closed thus automatically to form a succession of dots or dashes of predetermined length and at regular intervals.

The proper or desired length of the space intervals for a given speed of transmission may be attained by variation of resistance R9 which jointly with resistance R7, R8 and capacitance C5 determine the charging time required to restore the potential applied to tube V l to magnitude elTecting ionization. With the key closed on the dot side, resistor R2 may be varied to attain the desired length of the dots and with the key closed on the dash side, resistor REE may be varied to attain the desired length of the dashes.

the tube V5 is fully conducting, tube V6 is substantially non-conducting and the contacts of relay Ry I are held closed as by a biasing spring. Current through tube V6 is out off because the positive biasing voltage applied to its control grid through resistance Rl5 is, under the stated circumstances, nullified by the negative bias derived from the resistor REG in the divider network including it and the resistor Rl I.

When the key is moved to the dash side, the contact 4 is engaged to reduce the negative bias of tube V6 and so permit flow of current through relay Ry I of magnitude sufiicient to open its contacts and so open the short circuit across resistance RIZ. When as previously described, there is,

during the mark period, flow of current through resistor RIZ, the resulting voltage drop applied as negative bias to the control grid of tube V5 cuts off the anode current resulting in increase of the positive bias applied through resistors RM and R15 to the grid of tube V6 thus ensuring the contacts of relay Ry 5 remain open for the dash U period even though the key is prematurely moved With the usual straight or bug keys, most operators have diflicult in holding the clashes for like, precise lengths. With the keying system above described, a complete dot or clash may be made by merely hitting th key lever to make momentary contact on the dot or dash side. over, improperly shortened spacing between the dots or dashes of a character cannot be made because another mark cannot be started until there has intervened a space corresponding with the charging time of condenser C5.

The keying system described may be supplied from an source of suitably constant voltage; for example, the output voltage of a conventional filter-rectifier system S may be stabilized by a regulator tube VR. Because of low current demand, the filter system may be a simple resistance-capacity filter comprising condensers Cl, C2 and resistor R! l.

By way of example, there are given below circuit constants and components which have been successfully used:

The modification shown in Fig. 2 is the same as that of Fig. 1 with addition of tubes V5, V6, relay Ry l and associated components hereinafter listed. Except for features hereinafter described, the operation of this keying system-is an essentially the same as that of Fig. 1.

With the ke in either neutral or dot position,

away from the dash position. At conclusion of the dash period, if the key is then away from the dash position, all circuits return to their original condition.

It is characteristic of the modification shown in Fig. 2 that both dots and dashes continue for proper length even though the key is merely hit momentarily to close the dot or dash contacts and that there is no dependence upon the mechanical sluggishness of a spring contact (contact i of Fig. 1) during the dot period.

By way of example, there are listed below additional circuit constants and components used in this modification:

V56SF5 tube V66SN7GT (one section) BIL-250,000 ohms RI5250,000 ohms RIE75,000 ohms BIT-15,000 ohms The keying system of Fig. 3 is generally the same as that of Fig. 1 except that the relaxation oscillator utilizes a thyratron instead of two element gaseous discharge tube.

' The voltage divider network RIG, R20 and R2 I provides sufiicient negative bias for the control grid of thyratron tube V! to out off the anode current at the peak charging voltage of condenser C5. lhe resistor RH! for substantially eliminating grid emission may be omitted when the peak anode voltage is sufficiently low.

With the key in dot or dash position, the resistor R2] is shunted out through a circuit including the key contacts 2 or 3. Accordingly the grid-biasing voltage is reduced to such extent that the tube V1 momentarily conducts or fires to discharge the condenser C5. From this point on, the automatic action of the keying system is the same as described in connection with Fig. 1.

An advantage of this modification is that higher values of anode supply voltage may be used so permitting use of less sensitive relays.

By way of example, there are listed below circuit constants and components added in Fig. 3.

- RI850,000 ohms Rl915,000 ohms R2!l-2,000 ohms R2l200 ohms V1844 orsimilar thyratron tube.

Except for particular features herein specifically discussed, the keying system shown in Fig.

4 is similar tothat of Fig. 1. The principal differonce is the substitution of a polarized relay R112 for the relay By and the addition of tube V8 whose control grid is connected to the control grid of tube Vt of the multivibrator and in whose anode circuit is included one of thewindings of the relay Ry2. The other relay winding. is included in the anode circuit of tube V! as in Fig. 1.

With the key open and during space periods with the key closed in either position, the tube VI is conducting and tube V8 non-conducting. Under these circumstances, the relay contacts are in open-circuit position. During mark periods, the negative control-grid bias of tube V8, derived from resistors R22 and R23 is nullified by the positive potential appearing at the control grid of tube V3. At the same time, tube VI becomes non-conducting due to the negative potential then existing on its grid. Accordingly, the relay coils in circuit with VB and Vi become energized and de-energized respectively jointly to effect circuit-closing movement of the relay contacts.

This system is particularly suited for high speeds of transmission because of the positive action of the relay contacts.

The keying system shown in Fig. 5 is generically the same as that shown in Fig. l modified to include the features of the keying systems of both Figs. 2 and 4 and its operation need'not therefore be specifically described.

The keying system shown in Fig. 6 is generically the same as that shown in Fig. 1 modified to include the features discussed in connection with Figs. 2 and 3. Its operation therefore need not be specifically described.

The keying system shown in Fig. 7 is generically the same as that shown in Fig. l modified to include the features discussed in connection with Figs. 3 and 4. Reference is made to description of the operation of those systems for understanding of the operation of Fig. '7.

The keying system shown in Fig. 8 is generically the same as that shown in Fig. l modified to include features discussed in connection with Figs. 2., 3 and 4. Consequently, it is not necessary here to describe the operation of Fig. 8.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. An electronic keying system comprising a keying tube having a control electrode, a multivibrator directly coupled to said control elec trode, an oscillator, said oscillator being adapted to trigger said multivibrator and said keying tube, and keying means for initiating said oscillator whereby mark and space impulses are applied to said control electrode.

2. An electronic keying system comprising a keying tube having a control electrode, a multivibrator directly coupled to said control electrode, an oscillator, said oscillator being adapted to trigger said multivibrator thereby applying mark and space impulses to said control electrode, said multivibrator including impedances selectively to afford mark impulses of different predetermined length, and keying means for said oscillator operable concurrently to initiate operation thereof and to select the multivibrator impedance afiording desired length of mark impulse.

3. An electronic keying system comprising a keying tube having a control electrode, means for producing mark. and space impulses applied, to said control electrode comprising amultivi brator directly coupled to said control electrode and an oscillator directly coupled to said multivibrator, and keying means for initiating said oscillator and selectively determining the length of the mark impulses.

4..An electronic keying system comprising a keying tube having a control electrode, and means for providing mark and space impulses applied to said control electrode comprising a multivibrator and a relaxation oscillator coupled.

thereto, said multivibrator being directly coupled to said control electrode and adapted to be triggered bysaid relaxation oscillator, and keying means for said oscillator.

5. An electronic keying system comprising a keying tube having a control electrode, a multivibrator directly coupled to said control electrode, an oscillator, said oscillator adapted for triggering said multivibrator thereby applying mark and space impulses to said control electrode, akeying means for initiating said oscillator and selecting mark impulses when said keying means is operable from neutral position to clot or clash position, a multivibrator impedance for determining the duration of the mark impulses, a first tube having a shorting relay in its output circuit to short out said multivibrator impedance when said relay is deenergized, said first tube having a control electrode whose bias is changed by the actuation of said keying means to dash position thereby efiecting energization of said relay to remove the short circuit of said multivlbrator impedance, and a second tube responsive to completion of a dash impulse for varying the bias on said first tube to efiect deenergization of said relay provided said keying means is away from the dash position.

6. An electronic keying system comprising a keying tube having a control electrode, a multi vibrator directly coupled to said control electrode, a. gaseous discharge tube and reactanceresistance network, said discharge tube generating triggering impulses for said multivibrator for producing mark and space impulses applied to said control electrode, and a keying means for initiating said discharge tube and operable to one position completing a circuit including said discharge tube for generation of mark impulses of dash length and operable. to another position for completing a circuit including said discharge tube and in addition to modify the circuit constants of said multivibrator for mark impulses of dot length.

7. An electronic keying system comprising a keying tube having a control electrode, a multivibrator directly coupled to said control electrode for producing mark and space impulses applied to said control electrode, means for gen erating triggering impulses for said multivibrator comprising a resistance-reactance network and a discharge circuit therefore including a tube having a control electrode, and akey operable to one position for varying the potential 01 said lastnamed control electrode for generation of mark impulses of dash length and to another position in addition to modify the circuit constants of said multivibrator for generation of mark impulses of dot length.

8. A keying system comprising a keying relay, means for producing mark and space impulses, said means comprising a multi-vibrator and an oscillator coupled thereto, a keying tube having a. control electrode to which said impulses are applied, said multivibrator being directly coupled generation of to said control electrode, and said keying tube having an output circuit including said relay, and keying means for controlling said oscillator and for selecting circuit constants of the multivibrator to determine the length of the mark impulses.

9. A keying system comprising a dififerential keying-relay, means for producing mark and space impulses, said means comprising a multivibrator and an oscillator coupled thereto, two keying tubes having windings of said relay in their respective output circuits and having control electrodes to which said impulses are applied in opposite polarities, each portion of said multivibrator being directly coupled to a difierent one of said control electrodes, and keying means for initiating said oscillator and for selecting circuit constants of the multivibrator to determine the length of the mark impulses.

10. A keying system comprising a difierential keying-relay, means for producing mark and space impulses comprising a multi-vibrator and an oscillator coupled thereto, two keying tubes having windings of said relay in their respective output circuits and having control electrodes to which said impulses are applied in opposite polarities, each portion of said multivibrator being directly coupled to a difi'erent one of said control electrodes, and means for keying said oscillator and determining the length of the mark impulses comprising a key operable from neutral position to dot or dash position, a relay operable to change circuit constants of the multi vibrator, a first tube having said relay in its output circuit and a control electrode whose bias is changed by actuation of said key to dash position to effect actuation of said relay in one sense, and another tube responsive to completion of a dash impulse for varying said first tube bias to eifect actuation of said relay in reverse sense provided said key is away from dash position.

11. A keying system comprising a differential keying-relay, means for producing mark and space impulses comprising a multi-vibrator and an oscillator coupled thereto, said oscillator including a resistance-reactance network and an oscillator tube having a control electrode, two keying tubes having windings of said relay in their respective output circuits and having control electrodes to which said impulses are applied in opposite polarities, each portion of said multivibrator being directly coupled to a different one of said keying tube control electrodes, and keying means actuatable to dot or dash position to vary the potential of the control grid of said oscillator tube and concurrently to select circuit constants of the vibrator determining the length of the mark impulses.

12. A keying system comprising a differential keying-relay, means for producing mark and space impulses comprising a multi-vibrator and an oscillator coupled thereto, said oscillator ineluding a resistance-reactance network and an oscillator tube having a control electrode, two keying tubes having windings of said relay in their respective output circuits and having control electrodes to which said impulses are applied in opposite polarities, each portion of said mulivibrator being directly coupled to a different one of said keying tube control electrodes, a relay operable to select circuit constants of the multivibrator determinative of the length of the mark impulses, a relay-control tube having said relay in its output circuit and a control electrode; said relay acting to short circuit the above mentioned circuit constant when the relay is deenergized, a key actuatable to dot position to vary the control-grid potential of the oscillator tube and actuatable to dash position to vary said control grid potential of the oscillator tube and also that of control-grid of the relay-control tube, and another tube responsive to completion of a dash impulse for varying in reverse sense the potential of the control grid of the relay-control tube provided said key is away from dash position.

13. An electronic keying system comprising keying means, a keying tube having a control electrode, a multivibrator directly coupled to said control electrode, an oscillator for triggering said muliviibrator, said keying means operating to initiate said oscillator to thereby apply mark and space impulses to said control electrode, and an oscillator for triggering said multi-vibrator, said oscillator including a capacitor charged through an impedance, said impedance determining the duration of the space impulse, and a gas-filled tube for discharging said capacitor through said keying means to initiate the mark impulse.

14. An electronic keying system comprising a keying tube having a control electrode, means for producing mark and space impulses applied to said control electrode comprising a, multivibrator, said multivibrator being directly coupled to said control electrode, means for generating triggering impulses for said multi-vibrator comprising a gaseous discharge tube and a reactanceresistance network, and a key operable to either of two positions for adjusting the circuit constants of said multi-vibrator and completing circuits including said discharge tube for generating mark impulses of dash length and dot length respectively.

HARRY BEECHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,154,492 Clough Apr. 18, 1939 2,303,734 Garceau Dec. 1, 1942 2,421,022 Francis May 27, 1947 

